44 



LEA. ISAAC. LL.D. (Continued.) 



Description of a new species of Ilelix from California, and a 

 new Characteristic Form of certain American Colimacea'^. (Read 

 March 5th, 1852.) 



Vol. X, p. .303. ISd.'?. 



XoTE. — It will lie .•<cen thtit tlio Date uf Itcailiiig of many nf .Mr. Lea's Papers pncjdeil by several 

 years, that on the Title-page of the Volume in which they «ere issued. The Transactions were pub- 

 lished in Parts, but afford no internal evidence of the date of their issue, which has unfortunately 

 resulted in much uncertainty in regard to the jiriority of many of the specific names. Mr. Lea has 

 given in the Proceedings of the Academy of Natural Sciences, Vol. vii, p 236, a list of dates of publica- 

 tion, which I have deemed it important to insert here. — (See References in Parenthesis.) I have also 

 given the date on which some of the articles were issued in the Proceedings of the Philosophical 

 Society. Mr. Lea claims that the date of publication of a paver, is that on irhich it is read. 



IN PROCEEDINGS OF THE ACADEMY OF NATURAL SCIENCES, PHILADEL- 

 PHIA. 



Including the principal remarks made hij Mr. Lea, before (he Society. 



Letter from Mr. Lea, respecting change of orthography in spe- 

 cific names of Unionida?. Dated October 8th, 1842. (Read No- 

 vember 1st, 1842.) 



Vol. i, No. 2021, p. 215. December, 1S42. 



On the Genus Acost?ea, d'orbigny. (Communicated October 

 21st, 185L) 



Vol. V, No. 11, p. 277. October, 1S51. 



Remarks on the Periodicity of the Family Unionidse. (March 

 23d, 1852.) 



Vol. vi, No. 2, p. 5i. April, 1852. 



Description of a new species of Symphynote Unio. (Read 

 March 9th, 1852.) 



Vol, vi, No. 2, p. 54. April, 1852. 



Remarks on the Classification of the Naiades by their Anato- 

 tomical Differences. (April 6th, 1852.) 



Vol. vi, No. 2, p. 57. April, 1852. 



Notice of the My a Nod ulosa. wood. (June 14th.) 



Vol. vi, No. 9, p. 368. June, 1853. 



Letter to Dr. Leidy, on Castalia Sulcata and other Naiades. 

 (Read August 2d.) 



Vol. vi, No. 10, p. 370. .Aiiguft, 1853. 



